Hose assemblies used to carry fuels are well known in the art. The hose should preferably be strong and resistant to heat and chemical degradation. These hoses are subject chemical breakdown by the various fluids which flow through them. Further, these hoses are typically routed through the engine compartment of the vehicle to deliver fuel to the engines. These engines are hot and thus, the hoses used to carry fuel are subject to breakdown from the heat.
TEFLON hoses provide the necessary physical properties for carrying fuels. A major problem with these types of hoses is that when used alone, i.e., only a TEFLON liner or conduit, they tend to get bent during installation and they kink. This kink or deformation remains permanent and provides constant resistance to fluid flow through the hose. To solve this problem, one known hose assembly includes an inner TEFLON tubular member. The inner tubular member is surrounded by a tightly wound metallic braid. The metallic braid allows the TEFLON inner tubular member to bend to a certain degree without kinking. However, if bent past a certain point the metallic braid aids in the kinking of the inner tubular member. This assembly, has three major disadvantages. First, the metallic braid tends to abrade the exterior of the inner tubular member. This causes leaks from the inner tubular member. The second problem is that the exterior metallic braided casing is thermally and electrically conductive. More important is that the metallic braid will retain heat and transfer the heat to the fuel moving through the inner tubular member causing fuel system problems. Finally, when used in an automotive environment, the metallic braid transmits noise during operation of the vehicle which is undesirable.
Copending application U.S. Ser. No. 244,319 filed Sep. 8, 1988 and assigned to the assignee of the subject invention discloses a hose assembly for carrying fuels. The assembly includes an inner fluorocarbon polymer liner. In one embodiment, glass fiber is braided about the inner liner. An outer layer of a fluorocarbon foam is disposed over the glass fiber braided layer.
U.S. Pat. No. 4,111,237 to Mutzner et al issued Sep. 5, 1978 discloses a hose assembly. The assembly includes a polychloroprene inner liner. A glass fiber is then braided about the exterior of the inner liner. A rubber layer is then wrapped over the braided layer. A second braided layer of nylon is then placed about the rubber layer. Finally, a cover of polychloroprene is then extruded about the second braided layer.
U.S. Pat. No. 3,547,162 to Schuerer issued Dec. 15, 1970 discloses a plastic pipe assembly. The assembly includes an inner liner of a synthetic plastic made from cross linked olefinic polymers. A fiber braided layer is disposed over the inner liner. Finally, a foamed layer of synthetic plastic is disposed about the synthetic fiber reinforcement. By utilizing cross linked olefinic polymers, the system is deficient in that it cannot be used to carry vehicle fuels, as such fuels would degrade the inner liner. Further, this assembly requires a very thick outer casing to provide the necessary strength.